It's a word on its own!
However, there are some related words you might be thinking of:
* -ness: This is a common suffix used to form nouns from adjectives. You could say "tininess" to mean "the state of being tiny."
* -y: This is a common suffix used to form adjectives from nouns. You could say "tinier" or "tiniest" to compare sizes.
Let me know if you had another word in mind!